Table Editor And Planner, Or: Teapot!
These days, it may seem pointless having yet another spreadsheet program (and one that doesn't even know how to load Microsoft Excel files). Its compact size (130k for the ncurses executable, 140k for the GUI executable, 300k for the self-contained Windows EXE) and the fact that it can run across serial lines and SSH sessions make it an interesting choice for embedded applications and as system administration utility, even more so since it has a batch processing mode and comes with example code for creating graphs from data sets.
Another interesting feature is its modern approach to spread sheet theory: It sports true three-dimensional tables and iterative expressions. And since it breaks compatibility with the usual notions of big spreadsheet packages, it can also throw old syntactic cruft over board which many spreadsheets still inherit from the days of VisiCalc on ancient CP/M systems.
Here are some functional features in more detail:
- Cell Syntax
- Instead of the unflexible and complicated syntax used to address the values of cells in traditional spread sheets ("B1" or "R1C2"), teapot uses for a more functional approach: "@(1,2,0)". This results in an easily understandable syntax and despite the very few basic functions, very powerful semantics.
- Relative References
- As a direct result of this, instead of rewriting expressions during every operation that might alter references, and thus guessing user intentions and requiring awkward hacks like the "$A$1" syntax, references to other cells can be relative or via named cells: "@(x()-1, y(), z())", "@(NamedCell)", or even "@(x(TotalCost), y(Paper), z(IT_Department))"
- Formula References
- Formulas can be referenced directly via the "eval(...)" function instead of the usual copy-paste routine. By referencing a "mother formula" explicitly, changes and corrections to that formula are automatically propagated throughout the sheet.
- Three Dimensions
- In traditional flat spread sheets, you have to have the ability of hiding columns or rows to hide intermediate results. This indicates that two dimensions are not enough, which is why teapot is three-dimensional. The third dimension can be imagined like multiple layers on top of each other, usable without the awkwardness of multiple worksheets in established spreadsheet software.
- Unlike many other spread sheets, all values have a type, and all operations and functions check types. As a conclusion, adding a decimal number and a string will result in an error, instead of an (probably unwanted) result. This makes error detection much easier.
- Iterative Expressions
- teapot offers very comfortable iterative expressions, modelled after the clocked expressions in the current PhD work of Jörg Wittenberger at the University of Technology in Dresden, Germany. These expressions solve problems with circular dependencies in traditional spreadsheets and allow completely new algorithms and uses. In effect, these make teapot turing-complete. The proof is shipped as an example file, an implementation of Conway's Game of Life.
- Multiple UIs
- teapot offers several flexible and functionally equivalent user interfaces: A text mode interface using the standard (n)curses library, a modern graphical user interface using the light-weight FLTK library, and a batch processing mode for scripted calculations.
- Platform-Independent File Format
- The spread sheet file format is defined using XDR (External Data Representation as used by Sun RPC), which makes sure it is portable accross machines, especially regarding floating-point representations which may differ from system to system. XDR ensures that number format conversion errors are minimized. Due to this, usually no rounding or truncation is needed.
- Legacy File Formats
- Several additional file formats are supported: a custom, portable ASCII file format to ease automatic generation of sheets by shell scripts, standard CSV, SpreadsheetCalculator SC and Lotus 1-2-3 WK1 format. Microsoft Excel .xls and OpenDocument .ods are yet missing, but WK1 should allow data transfer including formulas.
- teapot can easily be extended by new functions in C. Instead of just adding all functions offered by other spread sheets, as few as possible were implemented as canonical as possible. So, if a function is lacking, it means that so far nobody needed it or there is a more general way to solve the problem. Don't hesitate to send me email to solve such issues.
- teapot can be internationalized and comes with English, Dutch, German and Polish message catalogs.
- Where possible, the KISS (Keep It Simple, Stupid) principle and the UNIX philosophy of "do one thing, and do it well" is employed. That means, instead of exporting every known format on earth, doing any task remotely related to spreadsheet calculation, there are interfaces to troff/tbl, LATEX, HTML and CSV which are well-suited for further processing, be it graphing, typesetting, accounting or anything else.
teapot is portable and doesn't depend on exotic libraries. It's quite probable that all dependencies are already available on your system:
- The Sun XDR library. It usually comes with the base operating system of modern UNIX variants, as part of the Sun-RPC subsystem. For example, the GNU C Library (glibc) includes the neccessary files. For Win32, Portable XDR is a compact implementation.
- Floating-point math, or an equivalent emulation. Usually only an issue for embedded devices.
- For the console version: A curses compatible library like ncurses or pdcurses
- UTF-8 in the console needs libncursesw, i.e. a moderately recent ncurses, and a UTF-8 locale setting.
- A build environment supported by CMake
- If you want the graphical user interface: A C++ compiler and the FLTK library, version 1.3.
Downloads / Version History
- Version 2.3.0, 2012-02-06 [Source][x86: Tar|DEB|RPM] [x86_64: DEB|RPM] [Win32: Installer|ZIP|standalone minimal EXE]
- Bug fixes, usability enhancements.
- Version 2.2.1, 2012-01-16 [Source][x86: DEB|RPM] [x86_64: DEB|RPM] [Win32: Installer|ZIP|standalone minimal EXE]
- Bug fixes, Font styles.
- Version 2.2.0, 2010-10-04 [Source][x86: Tar|DEB|RPM] [x86_64: Tar|DEB|RPM] [Win32: Installer|ZIP|standalone minimal EXE]
- UTF-8 support.
- Version 2.1.0, 2010-09-30 [x86: Tar|DEB|RPM] [x86_64: Tar|DEB|RPM] [Win32: Installer|standalone minimal EXE]
- New build system, improved documentation, Win32 portability.
- Version 2.0.2
- Improved low-resource builds, support linking without GUI help browser.
- Version 2.0.1
- Improved cell editing for FLTK interface, now supports inserting values from/pointers to other cells via mouse or keyboard. Fixed one crash, a few other bugs and quirks.
- Version 2.0
- Dumped GTK+ code in favour of FLTK. Faster, smaller, easier to understand and less buggy. Fixed a few other bugs and quirks.
- Version 1.9
- Inital GTK+ support, mostly complete and usable, but with a few caveats, thus considered beta quality.
- Version 1.09
- Last version written and maintained by Michael Haardt.
teapot is distributed under the terms of the GNU General Public License (GPL) Version 3.